Method of fitting circumferential seal members



B. DUFFY Oct. '29, 1963 METHOD OF FITTING CIRCUMFERENTIAL SEAL MEMBERS Filed 001:. '7. 1960 8 0 v 7 2 2 a 9 m M. F w III M I111 n u g a H HM 2 wi /I a m 4 II M 3 I. 2 m o 1 w Q 5 United States Patent 3,108,366 METHOD OF FITTING CIRCUMFERENTIAL SEAL MEMBERS Basil Duffy, Wellsville, N.Y., assignor, by mesne assignments, to Combustion Engineering, Inc., a corporation of Delaware Filed Oct. 7, 1960, Ser. No. 61,294 2 Claims. (Cl. 29-4195) plates are disposed in a passageway for a fluid to be heated Where the heat of the plates is transmitted thereto. The rotor is surrounded by a housing having end or sector plates formed with openings therein which provide for the passage of the fluids. To prevent mingling of the heating fluid and the fluid to be heated, radial seals are provided between compartments, and circumferential seals are provided along the end edge of the rotor to contact the adjacent face of the end plate and preclude fluid through the space therebetween.

In such heat exchange apparatus the rotor and surrounding housing become subjected to variations in temperature which alter the sealing relationship between sealing members and thus permit undesirable fluid leakage between passageways. Various attempts have been made to provide sealing means that may be manually or automatically adjusted to variations in clearance between the rotor and rotor housing. However, experience has shown that the operation of such sealing means is generally unsatisfactory and fluid leakage frequently surpasses perrnissible limits.

The present invention is therefore directed to a method of machining sealing means on the relatively rotatable parts of the heat exchanger to have an optimum sealing relationship throughout a wide range of temperature variations.

The invention will however be best understood upon consideration of the following detailed description of illustrative embodiment thereof when, read in conjunction with the accompanying drawings in which:

FIGURE 1 is a sectional elevation of a rotary regenerative heat exchanger having a sealing relationship according to the invention.

FIGURE 2 is a partial plan view in section as seen from line 2-2 of FIGURE 1.

FIGURE 3 is an enlarged sectional view of the arrangement utilized in machining the end edge of the rotary sealing element.

FIGURE 4 is an enlarged sectional View of the arrangement utilized in machining a sealing groove, in a sealing member of stationary housing structure as seen from line 44 of FIGURE 2.

In the drawings the numeral designates the cylindrical shell of a rotor that is divided into sector shaped compartments by radial partitions 11 connected to a rotor post 12 that is driven about its axis by a motor and reduction gearing shown diagrammatically at 13. The rotor compartments contain regenerative heat exchange material in the form of closely spaced metallic plates 14 which first absorb heat from a heating fluid entering the heat exchanger through a duct 15 from a boiler or other source to be discharged after passing ice over the heat transfer plates 14 through an outlet duct 16 to which an induced draft fan (not illustrated) is usually connected. As the rotor turns slowly about its axis the heated plates 14 are moved into the passageway for the fluid to be heated that enters the heat exchanger through duct -17. After passing over the heated plates 14 and absorbing heat therefrom, the heated fluid is conveyed to a boiler furnace or other point of use through an outlet duct 18.

A housing 20 enclosing the rotor 10 is provided at either end with end or sector plates 21 which are apertured at 22 and 23 to admit and discharge streams of the heating fluid and the fluid to be heated that are directed through the heat exchanger. To prevent mingling of the two fluids, radial seals 25 are provided along the end edges of the diaphragms, and circumferential seals 27 are provided at the end edges of the rotor shell to Wipe against confronting parts of the housing structure so as to seal oh? the annular space 28 surrounding the rotor.

According to the invention, a circumferential sealing means 27 is attached to each end edge of the rotor shell at opposite ends of the rotor to cooperate with fixed annular sealing members 32 attached to the rotor housing. The sealing means 27 is preferably flared outward at an angle approximately 45 in order that both axial and radial components of motion may be satis factorily resolved by a single member.

The sealing means or flange 27 is formed from sheet stock of substantially heavier gauge than that usually required for such applications since it is intended that this flange 27 remain essentially rigid throughout its range of operation. Moreover, an increased thickness of flange 27 will permit a greater degree of peripheral machining to reduce it to a completely circular form as required for optimum performance.

An annular sealing member 32 is aligned concentrically with flange 27 and attached to the housing end plate to provide a sealing member that cooperates with the flange 27 to preclude fluid flow therebetween. The sealing member 32 is formed 'from a rectangular bar of sufiicient thickness to provide substantial strength and rigidity even after a sealing groove 34 has been machined into its inner periphery.

After a sealing means or flange 27 has been properly aligned and secured to each end edge of the rotor, circumferential sealing members 32 are temporarily removed from the end plate 21 and replaced by a circumferential seal machining tool 35 having a cutting edge 36 arranged substantially normal to the sealing means 27 in order that any radial expansion of the rotor and sealing means attached thereto will progressively feed the end edge of the sealing means 27 on to the cutting tool. Since absence of the circumferential sealing members 32 on the end edge of the ducts will permit limited flow of fluid through the space between rotor shell and housing, it may be desirable to install a temporary baffle on the housing around the end edges of the rotor to reduce fluid flow therebetween and thus insure a more nearly constant fluid temperature within the ducts during the ensuing operation.

When the seal machining tool 35 is properly aligned and temporarily secured to the adjacent end plate 21, the rotor assembly is ready to be heated under operating conditions in order that the rotor and rotor housing may be forced to expand and otherwise distort as they would under normal operating procedures. Thus a heating fluid is admitted to duct 15 and a fluid to be heated is directed to duct 17 while the rotor is rotated about its axis in a conventional manner. As the rotor is brought up to temperature, it expands radially outward and tends to assume a somewhat dished configuration with the convex side of the dish lying adjacent the inlet 15 for the heating fluid commonly termed the hot end of the heat exchanger. As the edge of the rotor carrying the circumferential seal 27 expands radially outward and falls or rises in accordance with its structural arrangement, it feeds the edge of the seal 27 progressively to the cutting tool 35 which in turn forms it into a perfect circle at operating temperatures. The setting of the cutting tool is preferably such that it occupies the same position as the sealing member 32 it replaces. By this arrangement the circumferential seal 27 is formed to the size required for a perfect mating with circumferential sealing member 32 when it is finally repositioned on the end plate of the housing. After the temperature of the heat exchanger has been subjected to normal operating conditions, flow of fluids is terminated and the rotor is cooled suificiently to permit the circumferential seal member 32 to be repositioned on the end plate and secured thereto.

An upper seal ring machining tool 36 having a cutting edge 38 is then aligned with the end edge of the upper circumferential seal 27 and secured thereto while a lower seal ring machining tool 42 having a cutting edge 44 in alignment with the edge 46 of the lower circumferential seal is secured firmly to the lower seal to provide in effect an extended cutting edge for the circumferential seal 27 whereby expansion of the rotor during its rotation will feed a hardened cutting edge to the annular sealing members 32.

To impart maximum strength and rigidity to the upper and lower seal ring machining tools 36 and 42 during operation, the machining tools are preferably located in radial alignment with a diaphragm member. A machining tool so aligned will be more sensitive to thermal expansion of the rotor and will correspond more nearly to the exact configuration of the rotor for any particular temperature condition.

When cutting tools 36 and 42 are in position relative to upper and lower sealing members 32, the heat exchanger is again heated under normal operating conditions. Again a heating fluid and a fluid to be heated are admitted to the rotor, and the rotor is rotated about its axis in the usual manner to provide conditions identical to those encountered during normal operation. As the rotor expands and the outer edge tends to droop with an increase of temperature, the cutting tools 36 and 42 cut a groove in the sealing members 32 having a surface of curvature that corresponds to the position of the circumferential seals 27 for any normal temperature condition.

While this invention has been described with reference to the embodiment illustrated in the drawing, it is evident that various changes in the machining process may be made without departing from the spirit of the invention, and it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative only and not in a limiting sense.

Gil

What I claim is:

1. The method of providing an effective sealing relationship between annular sealing means on the end edge of a rotor and relatively fixed concentric sealing members on a rotor housing of a regenerative heat exchanger comprising the steps of positioning a cutting tool on the rotor housing radially outward from and confronting the sealing means on the radial end edge of the rotor, heating the heat exchanger through its normal operating range of temperature while the rotor is being rotated about its axis to thereby induce radial expansion of the rotor sufiicient to feed the annular sealing means on the rotor to the cutting tool whereby the sealing means will be machined to a circular configuration under operating conditions, cooling the heat exchanger, attaching a cutting surface to each annular sealing means carried by the rotor, and again heating the rotor while it is being rotated about its axis to induce thermal expansion of the rotor sutficient to feed the circular sealing means and the cutting tool affixed thereto radially outward to the concentric sealing member on the rotor housing thereby machining a surface on said sealing member having a curvature that corresponds to that of said annular sealing means.

2. The method of providing an effective sealing relationship between annular sealing means on the end edge of a cylindrical rotor and a relatively fixed concentric sealing means on a rotor housing of a rotary regenerative heat exchanger continuously throughout a range of temperature comprising the steps of substituting a cutting tool that confronts the end edge of the sealing means on the rotor for the sealing member on the housing, subjecting the heat exchanger to its normal operating range of temperature while the rotor is being rotated about its axis to thereby induce thermal expansion of the rotor sutficient to expand the sealing means radially outward to the cutting edge of the cutting tool and thereby form a circular sealing surface under operating conditions, terminating operation of the heat exchanger and permitting the rotor to cool, substituting the annular sealing member of the housing for said cutting tool and fixedly securing it to the rotor housing concentrically around the sealing means, aligning the cutting edge of a second cutting tool with the outboard edge of said sealing means on the rotor and fixedly securing it thereto, and again subjecting the heat exchanger to its normal operating range of temperature which induces radial expansion and axial deformation of the rotor to progressively feed the second cutting tool to the annular sealing member on the housing whereby a sealing surface of irregular configuration is formed thereon corresponding to that of said annular sealing means.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE METHOD OF PROVIDING AN EFFECTIVE SEALING RELATIONSHIP BETWEEN ANNULAR SEALING MEANS ON THE END EDGE OF A ROTOR AND RELATIVELY FIXED CONCENTRIC SEALING MEMBERS ON A ROTOR HOUSING OF A REGENERATIVE HEAT EXCHANGER COMPRISING THE STEPS OF POSITIONING A CUTTING TOOL ON THE ROTOR HOUSING RADIALLY OUTWARD FROM AND CONFRONTING THE SEALING MEANS ON THE RADIAL END EDGE OF THE ROTOR, HEATING THE HEAT EXCHANGER THROUGH ITS NORMAL OPERATING RANGE OF TEMPERATURE WHILE THE ROTOR IS BEING ROTATED ABOUT ITS AXIS TO THEREBY INDUCE RADIAL EXPANSION OF THE ROTOR SUFFICIENT TO FEED THE ANNULAR SEALING MEANS ON THE ROTOR TO THE CUTTING TOOL WHEREBY THE SEALING MEANS WILL BE MACHINED TO A CIRCULAR CONFIGURATION UNDER OPERATING CONDITIONS, COOLING THE HEAT EXCHANGER, ATTACHING A CUTTING SURFACE TO EACH ANNULAR SEALING MEANS CARRIED BY THE ROTOR, AND AGAIN HEATING THE ROTOR WHILE IT IS BEING ROTATED ABOUT ITS AXIS TO INDUCE THERMAL EXPANSION OF THE ROTOR SUFFICIENT TO FEED THE CIRCULAR SEALING MEANS AND THE CUTTING TOOL AFFIXED THERETO RADIALLY OUTWARD TO THE CONCENTRIC SEALING MEMBER ON THE ROTOR HOUSING THEREBY MACHINING A SURFACE ON SAID SEALING MEMBER HAVING A CURVATURE THAT CORRESPONDS TO THAT OF SAID ANNULAR SEALING MEANS. 